The present invention relates to an endless rotation hoop knife for a splitting machine.
The invention also relates to a transport device for a rotation hoop knife, in particular for a sharp rotation hoop knife. By the expression “sharp” is meant here that the blade is either sharpened or that the blade is still so sharp after operational use that cut wounds may occur unless additional protective measures are taken.
Finally, the invention relates also to methods for mounting and dismantling a rotation hoop knife, in particular a sharp rotation hoop knife.
A rotation hoop knife of the kind mentioned at the outset is known from DE 38 15 130 A1. In addition, German patent 328104 discloses a rotation hoop knife comprising holes which are engaged by driving pins of a drive wheel.
A rotation hoop knife of the known type is used as a cutting tool in a splitting machine. The rotation hoop knife is usually embodied in the form of an endless steel strip which runs over two discs, of which at least one is driven.
During the splitting process, a cloth-like piece of leather, for example, is guided against the rotation hoop knife circulating at high speed in order to split the piece of leather into two “splits” that are less thick.
To ensure uniformly high quality of splitting and to avoid the material tearing rather than splitting, the rotation hoop knife must have a sharp cutting edge. On the other hand, it is essential to prevent injuries occurring when handling the sharp rotation hoop knife.
The following procedure has become established as a way of meeting these requirements: When mounting the rotation hoop knife, it is first placed in blunt form onto the machine and tensioned. The rotation hoop knife is then driven and sharpened by means of a grinding device provided on the splitting machine. The grinding device is also used for regular sharpening of the rotation hoop knife during operation of the splitting machine.
If the rotation hoop knife can no longer be sharpened because its width is less than that required, and the rotation hoop knife must therefore be dismantled from the machine, it is essential to remember that the rotation hoop knife is usually still so sharp that cut wounds can occur. For this reason, the rotation hoop knife is blunted before it is taken off. The rotation hoop knife may not be removed from the splitting machine until this procedure has been completed.
Although this approach is widespread and practicable in principle, problems with certain applications arise in practice.
Metal fragments, or dust particles ranging from large to extremely fine can ensue not only when sharpening, but also when blunting a rotation hoop knife. This is not acceptable, however, in view of the standards of cleanliness for applications in the food industry or in medical technology. In such a case, especially when cleanroom conditions must be complied with, it would therefore be advantageous if sharpening of the rotation hoop knife were not carried out on the splitting machine.
However, this means that the rotation hoop knife would have to be transferred in the sharpened state from the grinding apparatus to the splitting machine. Given that the rotation hoop knife is usually ground until it is razor sharp, the slightest inattentiveness can result in the user incurring severe cut wounds. Such a procedure therefore requires suitable measures to prevent any risk of injury.